Reversal photographic elements produce a photographic image for viewing by a process of exposure of the element (film) to an image, development of the film to produce a negative of the image to be viewed, and then uniform exposure and/or fogging of residual silver halide and processing to produce a second, viewable image. In the preparation of a photographic elements for color reversal imaging, a coupler used to form a colored image is incorporated into a silver halide emulsion layer. Two methods have been used to coat film supports with emulsions in which a coupler is incorporated. In one, the coupler is added to the silver halide emulsion, and a single melt is made by heating the mixture to a temperature in the range of 35.degree.-46.degree. C. The resulting emulsion is filtered and then coated on the film support.
A second method provides better filtration control through a dual melt procedure in which the emulsion and coupler melts are made separately. Each is formed as a gelatin melt and heated to a temperature sufficiently high to render the melt flowable, typically about 40.degree. C. The separate melts are mixed together and then the resulting mixture is immediately coated on the support. The coupler composition is usually hydrophobic, such that the admixture is an oil-in-water emulsion.
Mixtures of different kinds or sizes of silver halide grains have been used in various applications, such as X-ray films. See Honda et al. U.S. Pat. No. 4,639,417, issued Jan. 27, 1987, and Kuwabara, U.S. Pat. No. 4,786,587, issued Nov. 22, 1988. A combination of a separately prepared tabular grain emulsion and a Lippmann emulsion have been used for the purpose of transferring a dye from the silver salt grains to the tabular grains. See European Patent Publication No. 267,483.
High aspect ratio tabular grain silver haloiodide emulsions have been used in color reversal imaging to provide a variety of photographic advantages, such as improvements in speed-granularity relationships, increased image sharpness, and reduced blue speed of minus blue recording emulsion layers. Ellis, U.S. Pat. No. 4,801,522, issued Jan. 31, 1989 describes a process for preparing such tabular grains. It has been further recognized that the photographic properties of the tabular emulsion can be further improved by using an emulsion layer containing a blend of tabular silver haloiodide grains and relatively fine grains made of a silver salt more soluble than silver iodide. See Sowinski et al., U.S. Pat. No. 4,656,122, issued Apr. 7, 1987. Sowinski et al. give examples of using fine grains of silver bromide (AgBr), silver chlorobromide (AgClBr) or silver chloride (AgCl) with tabular grains of silver chlorobromoiodide (AgClBrI). However, this patent does not recognize that the manner in which the fine grains are added to the tabular grains in forming the photographic element can influence the performance of the resulting film.